Lock bottom for paperboard container



Jilly 22, 1958 V 1.. M. SOJA LOCK BOTTOM FOR PAPERBOARD CONTAINER Filed Nov. 8, 1956 United States Patent "(3 LOCK BOTTOMIFORL Lawrence'M'. Soia, Chicago, Ill'., assignor to Stone Con- 'tainer Corporation, Chicago, Ill.

Application November-8, 1956-, SeriahNo..-62;1,13.4. 1' Claim. (Cl. 229-49 is known, the application ofprior structures to the. closing,

ofi ofthebottom of a container have been subject to severe disadvantages; I Thestructure described herein is intended to'be' assembled by: unskilled persons perhaps a housewife: :or" the i like; without the use of glue'orfastener's: of: anylci'nd, so

thatthe: structure maybe collapsed whernnot in'use. Obviously fastening meanswill provide additional sup port but such means are". neither" essentiali'nor' required for achieving the advantagesofthe inventions "Prior-i structures have been complex and "difiicult to manufacture and" assemble, "besides being expensive. Where attemptshave been mad'e'to simplifythe' structure, there-has been a sacrificeof strength 'and"'d-urabilifty; An important object of the invention is to provide anextremely'simple structure, easy to "assemble,

economical, andhaving unusual strength.

An important object of the invention container in which the structure is locked in cIosed condition by means. provided on the hottom o'fiithe container as .a. part ofthe closure, said meansicomprisingra -fl-ap substantially of the same size and contours as theri nteri'or sectionalconfigur'ation" of the"'conta'iner so .as.- to fully cl'ose .ofifthebottom ofthe container.

IALfurther import-ant ob ect of thekinvention lies in. the provisionof alock'bottom "for. a container having a structure which utiIiZes the weight offthe contents to as'sistin resisting undesired opening oftheelosure-thmugh downward push-out.

Many additional-.objectsandadvantages of the invention will occur to those skilledin this art, as the descripti'onof the preterred-embodimentproceeds: For-example, certain structural details such as the substantial overlap of certain flaps are considered of importance, but will become apparent hereafter.

In the drawing in which the preferred embodiment is illustrated:

Fig. 1 is a perspective view of the type which may have the invention therein;

Fig. 2 is a bottom perspective view of the container showing the elements of the lock bottom, or closure as it may be termed, prior to final assembly;

Fig. 3 is a median sectional view through the closure in assembled condition along the line 3-3 of Fig. 4 in the indicated direction; and

Fig. 4 is a bottom plan view of the container in closed condition with a portion broken away to show details of the structure.

of a paperboard container embodied comprises-the provision of. a-lock. bottom structure fora paperboard The invention as illustrated hereinis, embodied i'na hamper for storing, and; transport-inggclothing. or. laundry, but. it should be appreciated that the-invention is equally applicable to containers for many other commodities, incl'u'di'ng hardware, provisions, and .the'like. The. illustration anddescription of the containeri's therefore merely one example of the use of the. lockbottom.

Thecont-ainer 10 is shown in Fig. l as a hamper having front and rear walls 12. and 14; andside wallsl I6 and 18, av closure or lock bottom not visible. in..Fig. 1,, and. a hinged cover member 20 withlockingflap 22., Container 10 and its parts. are preferably formed.rom. an integral sheet of. paperb'oard,.fo'rexampldeorrugated. paperboard, suitably blanked. and rendered tubular.

throughout. the length of the walls by. tape or. metal.

stitching as wellknown. Additionalrefinements. notof importance. to the invention except where emhodi'edi'n. the hamper of Fig. 1 comprise hand-holesv 24in the, side walls 16 and; 18 and ventilatingholesv 26..

, consid'eringfigsl, 3 and 4,,the. closure or. lockhottom. generally may be, designated .30 andflis. ormed'..of.IfQur parts-32', 34',;'36;f331 "There. is an innerrectangular. pressure fl'ap'S'Z which is; substantially ofzthe, samesizeandi contour. as. the interior of, the. container 10; iota horizontal; plane; an intermediate slotted" locking 'fiapl 3.41 Of'substan-f daily the same. size andfshape asfiap, 3.2;; and' tlieflthio pressure flap 32 is. integralwith= andlhingpdlytconei nected to the wall. 1'2a1bng, crease or scoreJihe-flllf. It is always positioned on. the interior of; the container 1'0 andyduring. assembly is'bentjup'into the container-aha.

' considerable. angle to enable theiinterlocking and.overlap ofjthe other flapswhich willbedescribe'd 1.. The intermediate slottedjlhcking flap .34. is integral. with and hingedly connected to the'wa1l14 along crease W or scoreline 42-. During assembly'i't i's thefirst part to; p

be positioned, being swung over the 01. of the container 10' to. close. the. same. .QIILhas. twoslots.

etcw se open end" 4f4'land 46 which-flare disposedgparallel o,one.. a. uc .therv and transverse, of the. length of flap. 341, =Preferalfzbgthe.

. slots-'44. andmh are arranged perpendicular. tojshorel 42' and are. spaced. equally.fiom..the,ends-.4.&}.aud..5(l,,

respectively of the flap 3.4,, aboutT one '.qnarter.of.the.fiap

length. The length of the slots;i44ands4oj u g less than the wid f flag p i The two. friction flaps 3.6. andj38. are; integraliwithaand hingedlyconnected respectively tothe'wrll'sgldand'. 1,8,; long, th creases or score lines 52. .andQ'SA, respectiiielys Both of the friction 'fl'aps are, identical. in size and configuration; l Each has a portion adjacent its hingedeiease tline. which is of isosceles, trapezoidal configurationiheing designatedrespectivel'y 56' and '58, and'at'ltheliarwvlt ends; of the. portionsSfi, and 58. there,are ,p r.ovided the tiin'gue portions.61Eandhzjrespectivelyjw""hIafamclau 1' Lin, configuration. The wid'thof theisosceles tr'ape'zoidbhis the same as the distance between the end 48 and the slot 44, and likewise the width of the isosceles trapezoid 58 is substantially the same as the distance from the end 50 to the slot 46. This latter width is measured perpendicular to the respective score lines 52 and 54. The

width of the tongue portions 60 and 62 considered parallel to the score lines 52 and 54 respectively is the same as the length of the slots 44 and 46 so that the tongue portions may be inserted in the slots during the assembly of the device in the manner which will be described.

In assembling the closure or lock bottom, after the container 10 has been manipulated to form the tube and it will be appreciated that the entire structure may be flattened out for storage and shipment), the pressure flap 32 is pushed up inside the tube so that the bottom of the container has the appearance shown in Fig. 2. The next step is to swing the intermediate flap 34 upon the open bottom in the manner as shown in Fig. 3. In the next step each of the flaps 56 and 38 is manipulated to insert the tongue portions 60 and 62 through the respective slots 44and 46 from the bottom of the flap 34 .so that both of the tongue'portions 60 and 62 extend upwardly inside the container as indicated in the broken lines 60' and 62' of Fig. 3. When this has been done, the isosceles trapeze-ids 56 and 58 will overlie the bottom face of the flap 34. Ifdesired, there may be a score line 64 between the two parts of the flap 36 and a similar score line 66 between the two parts of the flap 38 to facilitate the bending of the tongue portions 60 and 62. Following this, the party assembling the structure may reach inside the container from the top thereof and manipulate the protruding flaps 60 and 62' so that they overlap one another in the manner shown in Figs. 3 and 4. When this has been done, the pressure flap 32 is pressed down o'ntop of the overlapped tongue portions, and the assembly is completed. The pressure flap 32 may fit rather snugly on the interior of the container so that, even with no articles in the container, the assembly will not force the pressure flap 32 upward. It should be appreciated that the all-over length of flaps 36 and 38 measured perpendicular to the score lines 52 and 54 respectively is substantially greater than half the distance between score lines 52 and 54 so that, when assembled, there will be a substantial overlap. This overlap very greatly increases the frictional engagement between the flaps 36 and 38 to prevent their separation and the consequent spreading of the container. The pressure flap 32 adds to this friction. The direction of movement of the pressure flap 32 upon the overlapping tongue portions 60 and 62 is as indicated in Fig. 3 by the arrows.

Any tendency of the assembly described to come apart and the bottom. of the container to accidentally open is resisted by the frictional face to face engagement of the two tongue portions 60 and 62. This friction obviously will be enhanced when articles of anything of weight is placed in the container to increase the pressure of the pressure flap 32.

It will be appreciated that considerable variation in the structure is readily capable of being made without departing from the principles of sacrificing any of the advantages of the invention. For example, the slots 44 and 46 need not be parallel with the ends 48 and 50 of the intermediate flap but may be arranged at an angle thereto with corresponding changes in the configuration of the flaps 36 and 38, if desired.

The structure lends itself readily to the economical construction of reusable containers and as well for containers which are intended for use in storage, transportation and the like. It is again emphasized that the upper structure of the container is immaterial and forms no part of the invention.

What it is desired to secure by Letters Patent of the United States is:

A collapsible, re-usable container of stiif paperboard material adapted to support a substantial weight therein,

comprising a sleeve of substantially rectangular crosssection having front, rear and opposite side walls and an open bottom end, a rectangular pressure flap having one edge thereof hingedly connected to the lower edge of said front wall, a rectangular locking flap having one edge thereof hingedly connected to the lower edge of said rear wall, said flaps having substantially the same configuration as the cross-section of said sleeve, said locking flap having a pair of slots in the intermediate body portion thereof extending transversely of the hinged connection thereof, said slots each being spaced from an adjacent end of the locking panel a distance approximately equal to one fourth of the panels length, a friction flap hingedly connected to the lower edge of each of said side walls, said last flaps each including a pair of segments comprising, a first segment of isosceles trapezoidal configuration, the trapezoidal segment being connected to the said lower side wall edge along the entire extent thereof and the width of each trapezoidal segment considered transverse to its hinge connection being substantially equal to approximately one fourth of the length of said locking flap, the second segment of each friction flap being of elongated rectangular form and having a hinge connection with the respective trapezoidal segment and the width of said second segments being substantially equal to the length of' said slots, said pressure, locking, and friction flaps being disposable in said open bottom end of said sleeve in the provision of a multi-ply closure formation and wherein said locking flap is disposed substantially in the plane of the lower edges of said front, rear and side walls, the said trapezoidal segments being disposed beneath said locking flap and the said rectangular segments extending through said slots and being disposed in overlying relation between said pressure flap and said locking flap, the .said rectangular segments being of a length substantially equal to the distance between said slots and having the adjacent faces thereof in frictional engagement and the opposite faces thereof in frictional engagement with the pressure flap and the locking flap, whereby the weight of the contents of the container press the said rectangular segments together and against the locking flap frictionally locking same. to prevent their separation and withdrawal from the slots.

References Cited in the file of this patent UNITED STATES PATENTS 241,409 Osborn May 10, 1881 306,532 Schmidt Oct. 14, 1884 506,403 Johnson Oct. 10, 1893 690,496 Webb Jan. 7, 1902 1,925,113 Rutledge Sept. 5, 1933 2,021,559 Lengsfield Nov. 19, 1935 2,186,777 Best Ian. 9, 1940 2,528,256 Tichenor Oct. 31,1950

FOREIGN PATENTS Great Britain 1900 

